Systems and methods for active interference cancellation to improve coexistence

Abstract

This disclosure describes techniques for providing active interference cancellation in a wireless communication system having a Bluetooth transmit chain and a WLAN receive chain. A signal sampled from the Bluetooth transmit chain is gain and phase adjusted to offset interference in the WLAN receive chain. A quadrature phase shifter may be used to generate quadrature components of the sampled signal that are selectively combined to achieve a desired phase adjustment. The phase shifter may be stabilized by a variable capacitor. These techniques may be extended to MIMO systems.

Description

FIELD OF THE PRESENT INVENTION[0001]The present disclosure generally relates to wireless communications and more particularly relates to systems and methods for enhancing the coexistence of wireless local area network (WLAN) and BLUETOOTH® (“Bluetooth”) networks.BACKGROUND OF THE INVENTION[0002]The recent proliferation of devices employing wireless technologies has led to the incorporation of devices with multiple wireless communication systems. Bluetooth is often used to connect and exchange information between mobile phones, computers, digital cameras, wireless headsets, speakers, keyboards, mice or other input peripherals, and similar devices. Bluetooth allows for the creation of a personal area network (PAN) between a master and up to seven slaves. WLAN systems, such as those defined by IEEE 802.11 protocols, are typically directed to longer range communications and larger networks. WLAN communications provide relatively high data rates over relatively long distances, offering a...

AI Technical Summary

Benefits of technology

This patent is about a system and method for reducing interference between Bluetooth and WLAN signals in a wireless communication device. The system includes a sampled signal, a polyphase filter quadrature radio-frequency (RF) phase shifter, and a combination logic that adjusts the phase of the sampled signal by weighting and combining the quadrature components. The system also includes an absolute phase adjustment to compensate for variations in the load applied to the phase shifter. Additionally, the system can adjust the amplitude of the output signal based on feedback from the WLAN receive chain. The patent also describes a device that includes the active interference cancellation module and a load adjuster to reduce variations in the load applied to the phase shifter. The system and device can improve wireless communication performance and stability.

Problems solved by technology

For example, the physical proximity of the Bluetooth and WLAN modules may result in the transmission of one radio generating interference that impairs reception in the other radio.

These problems may be exacerbated when the design of the device involves the sharing of a single antenna among both radios.

In the context of devices employing Bluetooth and WLAN radios, a Bluetooth transmission can be characterized as interference with respect to WLAN reception of the desired signal.

Although the bandwidth of the Bluetooth signal is fairly narrow at 1 MHz as opposed to the 20 or 40 MHz of a WLAN channel, the Bluetooth protocol utilizes frequency hopping, making it difficult for the WLAN radio to settle on a stable channel and desensitization of the WLAN receiver may result.

As such, WLAN reception performance may be degraded if interference due to the Bluetooth transmission is not mitigated.

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